基于气垫船减阻结构的低发热高刚度超精密液体静压轴承的基础研究

The application of liquid hydrostatic bearings on the motorized spindles of precision milling machine tools will greatly improve the machining accuracy of this type of machine tools. However, due to the serious shear heat generation of oil film at high speed, it is difficult to meet the speed requirement of such machines and the main solution at present is drag reduction. In view of the current situation that the super-hydrophobic micro-structures have limited drag reduction effect and are difficult to be prepared on the bearing surfaces, inspired by the working principle of hovercraft, this project proposes a hovercraft drag reduction structure (i.e. oil land air pad reduction structure) suitable for liquid hydrostatic bearings, which is expected to solve the problem of heat generation at high speed from the bottom layer. Through the combination of theory and experiment, three basic contents are systematically studied including drag reduction mechanism, stiffness law and precision law. Taking the active air pad drag reduction mechanism and the gas-liquid film thickness control method in the micro-gap as the key scientific problems, the heat generation is greatly reduced by establishing a gas-liquid two-phase film through the oil land air pad reduction structure, the drag reduction effect is quantitatively characterized by the two-phase fluid velocity variation model between two parallel plates, and the influence on heat, stiffness and precision is adjusted by the gas-liquid film thickness control method through adjusting the throttling resistance and inlet pressure. Furthermore, the hydrostatic bearings with three advantages of low heat generation, high stiffness and ultra precision are obtained, which can be widely used for precision milling machine tools, ultimately improving the processing and manufacturing capabilities of precision machine tool components and complete machine tools in China.

液体静压轴承在精密铣削类机床电主轴上应用，将大幅提高该类机床加工精度，但由于高速下油膜剪切发热严重，难以满足该类机床速度要求，目前主要解决途径是减阻。本项目针对超疏水微织构减阻效果有限且很难在轴承曲面上制备的现状，受气垫船工作原理启发提出了一种适用于液体静压轴承的气垫船减阻结构（即封油面气垫减阻结构），可以从底层解决高速油膜发热难题，理论和实验相结合系统研究基于这种新结构的液体静压轴承的减阻机理、刚度规律和精度规律等三项基础内容，以微间隙有源气垫减阻机理和气液膜厚控制方法为关键科学问题，通过封油面气垫减阻结构建立气液两相膜大幅减小发热，通过两平行板间两相流体速度变化模型定量表征减阻效果，通过调整节流阻力和进口压力控制气液膜厚调整对发热、刚度和精度的影响，进而获得具有低发热、高刚度和超精密等三个优点的液体静压轴承，可以在精密铣削类机床上广泛应用，最终提高我国精密机床部件和整机的加工制造能力。

本项目受气垫船工作原理启发提出了一种适用于液体静压轴承的气垫船减阻结构（即封油面气垫减阻结构），可以从底层解决高速油膜发热难题，理论和实验相结合系统研究了基于这种新结构的液体静压轴承的减阻机理、刚度规律和精度规律等三项基础内容。建立了两平板间两相流体速度变化模型，得到了气垫减阻率的理论近似解，发现气垫减阻可能是微织构减阻的极限状态，并通过实验观测了静压油垫气液两相膜的形成和温度变化。建立了气液两相膜等效刚度串并联模型，得到了刚度减少率的理论近似解，并通过实验测量了有气垫和没气垫时的刚度变化。建立了单频率谐波误差影响模型，得到了误差均化系数的理论近似解，并通过实验测量了有气垫和没气垫时的精度变化。以微间隙有源气垫减阻机理和气液膜厚控制方法为关键科学问题，初步得到了具有低发热、高刚度和超精密等三个优点的液体静压轴承，为其在精密铣削类机床主轴上广泛应用提供了理论基础。依托项目支持，发表SCI论文6篇，申请发明专利1项，培养在读研究生1名和本科毕业生2名，搭建了基于封油面气垫减阻结构的AH5030静压油垫实验台1套和AH60静压轴承实验台1套。